JP3336032B2 - Refrigeration circuit with injection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration circuit having an injection circuit used for cooling a gas when a predetermined temperature atmosphere is obtained by cooling the gas and controlling the temperature of the cooled gas by a heater.

[0002]

2. Description of the Related Art A refrigerant such as Freon R502 has been used for a long time in such a refrigeration circuit in an environmental test apparatus or the like. However, in recent years, this kind of refrigerant has a risk of destruction of the environment. And so on. Due to the characteristics of the substitute refrigerant such as Freon R22, when adiabatic compression is performed by the compressor in the refrigeration circuit, the refrigerant temperature at the compressor discharge section is likely to be high, which causes deterioration of the refrigerant, deterioration of the compressor oil, and the like.

Therefore, when this type of alternative refrigerant is used, as shown in FIG. 4, a liquid receiver 3 is provided in the main circuit 6 at the outlet side of the condenser 2 and accumulated in the liquid receiver 3. A part of the condensed liquid refrigerant flows into the injection circuit 7 connected to the injection port (intermediate injection port) 11 of the cylinder of the rotary or scroll type compressor 1 including the expansion mechanism 71. Is injected into the compressor 1 to cool the compressor 1 and prevent abnormal temperature rise.

There is also a system in which a part of the condensed refrigerant is returned to the suction port of the compressor. However, as described above, returning to the intermediate injection port has a greater cooling effect on the compressor.

[0005]

However, since the liquid receiver 3 generally has a considerably large proportion of the refrigerant capacity with respect to the refrigerant capacity of the circuit 6, when the whole refrigeration circuit is viewed, 3 requires a large amount of expensive refrigerant, which is uneconomical. Refrigeration circuits used in various devices such as environmental test devices are usually required to have as small a circuit volume as possible in order to reduce the size of the device and save expensive refrigerant. Therefore, the use of the receiver to increase the refrigerant capacity is not desirable.

Accordingly, the present invention is directed to a refrigeration circuit having an injection circuit used for cooling a gas when a predetermined temperature atmosphere is obtained by cooling the gas and controlling the temperature of the cooled gas by a heater. Compared to using a compressor, the amount of refrigerant can be greatly reduced, and yet the condensed liquid refrigerant can be easily and reliably supplied to the injection circuit to prevent abnormal temperature rise of the compressor and stabilize its operation state. It is an object to provide a refrigeration circuit including an injection circuit.

[0007]

Means for Solving the Problems The present inventor has conducted studies to solve the above problems and found the following. Generally frozen
The circuit has a condenser, expansion mechanism and evaporation at the refrigerant outlet of the compressor.
The evaporator refrigerant outlet is connected to the compressor
Circuit connected to the medium suction port (hereinafter called this circuit)
U) Includes, but is circuit designed refrigerant flowing into the expansion mechanism exits the condenser of the present circuit are all liquid refrigerant, when the temperature is controlled a predetermined space, the evaporator of the refrigeration circuit In the case where the gas is cooled and the cooled gas is controlled to a desired temperature by appropriate operation of the heater, when a high-temperature atmosphere is to be obtained in the space, the expansion mechanism of the present circuit exits from the condenser. The refrigerant flowing into the compressor may be a refrigerant mixed with gas, and it is sufficient that the liquid refrigerant flows through an injection circuit leading to the compressor and the compressor operates normally. From such a viewpoint, it is desired that the refrigerant capacity in the refrigeration circuit be kept to a necessary minimum to save the refrigerant.

In such a refrigeration circuit, when the refrigerant that has exited the condenser is a gas mixture, a part of the refrigerant is separated into gas and liquid, and the gas refrigerant is returned to the main circuit. Only the liquid refrigerant is supplied to the injection circuit. May be configured to flow.
Moreover, a commercially available gas-liquid separator can be used for the gas-liquid separation, and the refrigerant capacity of the refrigeration circuit can be further reduced by employing the gas-liquid separator having a smaller refrigerant capacity than the conventional liquid receiver. Even if all the refrigerant leaving the condenser becomes liquid refrigerant, the refrigerant flowing in this circuit is left as it is, and a part of the liquid refrigerant flowing into the gas-liquid separator is If this is allowed to flow through this circuit, there is no hindrance to the operation of the refrigeration circuit.

The present invention is based on such knowledge and provides a refrigeration circuit provided with an injection circuit used for cooling a gas in order to obtain a predetermined temperature atmosphere by cooling the gas and controlling the temperature of the cooled gas by a heater. , Compression
A condenser, expansion mechanism, and evaporator are sequentially arranged at the refrigerant discharge port of the machine.
Connected with a pipe, the refrigerant outlet of the evaporator is connected to the refrigerant suction port of the compressor.
Pipe the connected circuit has a (present circuit), the present gas-liquid separator for gas-liquid separation part of the refrigerant exiting the <br/> condenser at the condenser outlet side Branch connection to the circuit, the gas outlet of the gas-liquid separator is connected back to the main circuit, and the liquid outlet of the gas-liquid separator is connected to the injection circuit including the expansion mechanism and connected to the compressor injection port. A refrigeration circuit provided with an injection circuit characterized by being connected.

[0010] The gas-liquid separator can be appropriately selected and employed from those which are generally commercially available. In addition, since only a part of the refrigerant flows through it, the capacity thereof is significantly smaller than the capacity of the liquid receiver provided in the conventional refrigeration circuit with an injection circuit. When returning the refrigerant separated by the gas-liquid separator to the main circuit, besides returning it to the inlet side of the expansion mechanism in the main circuit,
Returning to the inlet side of the evaporator downstream from the expansion mechanism of the present circuit via another expansion mechanism or returning to the suction port side of the compressor downstream from the evaporator may be considered.

[0011]

According to the refrigeration circuit of the present invention, the refrigerant is compressed by the compressor and then condensed in the condenser. A part of the refrigerant flowing out of the condenser flows into the gas-liquid separator, and the remainder flows through the circuit as it is. Then, it flows into the evaporator via the expansion mechanism of this circuit, where heat is exchanged, and then returns to the compressor inlet again. When the refrigerant flowing into the gas-liquid separator is a gas-mixed refrigerant, the refrigerant is separated into a gas-liquid and a gas-phase refrigerant or a part of the gas-phase refrigerant and the liquid-phase refrigerant. In such a case, a part thereof is directly returned to the inlet side of the expansion mechanism of the present circuit, or is returned to the refrigerant inlet side of the evaporator or the suction side of the compressor via another expansion mechanism. Returned to this circuit,
Merges with the refrigerant flowing through the circuit. On the other hand, all or part of the liquid refrigerant in the gas-liquid separator flows into the injection circuit, flows through the expansion mechanism of the circuit to the injection port of the compressor, and is used for cooling the compressor and from the main circuit. To the refrigerant.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows one embodiment, FIG. 2 shows another embodiment, and FIG. 3 shows still another embodiment. In any of the embodiments, the evaporator 5 is disposed in a space where a predetermined temperature atmosphere is to be obtained, for example, a space in a test tank of an environmental test device such as a thermostat, and is used for cooling gas in the space. In addition,
The gas cooled in this manner is controlled to a predetermined temperature by appropriately operating a heater (not shown) provided usually on the downstream side of the evaporator.

The three embodiments have the following common points. That is, in each of the refrigeration circuits of the embodiments, a compressor (here, a scroll compressor) 1 having an intermediate injection port is included, and the condenser 2, the expansion mechanism 4, and the refrigerant discharge port 13 of the compressor are provided. An evaporator 5 is sequentially connected to a pipe, and a refrigerant outlet of the evaporator 5 is connected to a refrigerant inlet 1 of the compressor 1.
The circuit 6 is formed by pipe connection to the circuit 2. The refrigerant used is Freon R22 in this example.

In the embodiment shown in FIG. 1, a branch pipe 80 is connected to a portion of the circuit 6 on the outlet side of the condenser 2, and a gas-liquid separator 8 is connected to the branch pipe. The gas-liquid separator 8 may be a commercially available gas-liquid separator, and its capacity may be significantly smaller than that of the liquid receiver 3 in a conventional refrigeration circuit having an injection circuit. Liquid refrigerant outlet 8 of separator 8
1 is connected to an injection circuit 7, which includes an expansion mechanism 71, and an outlet of the expansion mechanism is connected to an injection port 11 of the compressor 1. Further, the gas-phase refrigerant outlet 82 of the separator 8 is connected back to the main circuit 6 downstream of the branch point and upstream of the expansion mechanism 4 by a pipe 91.

In the embodiment shown in FIG. 2, the gas-phase refrigerant outlet 82 of the gas-liquid separator 8 has a pipe 92 including an expansion mechanism 93 downstream of the expansion mechanism 4 of this circuit and upstream of the evaporator 5. It is connected back to the circuit 6. The other points are the same as those of the embodiment of FIG. In the embodiment shown in FIG.
Is connected back to the circuit 6 downstream of the evaporator 5 and upstream of the suction port 12 of the compressor 1 by a pipe 94 including another expansion mechanism 95. Other points are the same as those of the embodiment shown in FIG.

According to each of the embodiments described above, the refrigerant is compressed by the compressor 1 and then condensed in the condenser 2, and a part of the refrigerant flowing out of the condenser 2 flows into the gas-liquid separator 8 and the remainder Flows through the circuit 6 as it is. The refrigerant flowing in the circuit 6 expands in the expansion mechanism 4 in the circuit and flows into the evaporator 5, where heat exchange is performed, and then returns to the suction port 12 of the compressor 1.

On the other hand, the refrigerant flowing into the gas-liquid separator 8 is separated into gas and liquid by the separator, and all or a part of the separated liquid refrigerant flows into the injection circuit 7 and the expansion mechanism 7 there.
After that, the refrigerant flows into the injection port 11 of the compressor 1, thereby cooling the compressor 1 and joining the refrigerant from the circuit while preventing abnormal temperature rise of the compressor. The gas-phase refrigerant or a part of the gas-phase refrigerant and the liquid refrigerant separated by the gas-liquid separator 8 is returned to the inlet side of the expansion mechanism 4 of the circuit 6 in the embodiment of FIG. Merges with the refrigerant and flows through the circuit as it is.

In the embodiment shown in FIG. 2, the gas-phase refrigerant or a part of the gas-phase refrigerant and the liquid refrigerant that has exited the separator 8 is returned to the main circuit through the expansion mechanism 93, and merges with the refrigerant there to evaporate. After flowing into the compressor 5, the heat is exchanged and the flow returns to the compressor 1. In the embodiment shown in FIG. 3, the gas-phase refrigerant or a part of the gas-phase refrigerant and the liquid refrigerant that has exited the separator 8 is returned to the main circuit 6 through the expansion mechanism 95, merges with the refrigerant, and flows to the compressor. Return.

In any of the above embodiments, the separator 8
When all of the refrigerant flowing into the separator 8 is a liquid refrigerant, a part of the liquid refrigerant in the separator 8 flows to the injection circuit 7, and the remainder is returned to the main circuit. In any of the above embodiments,
Since the used gas-liquid separator 8 has a small capacity, even if the gas-liquid separator 8 is provided, the capacity of the refrigerant in the entire refrigeration circuit can be reduced in the refrigeration circuit using the conventional liquid receiver. Compared with this, the whole can be provided at a low cost. Also, the compressor injection port 11
, The liquid refrigerant always flows, so that the operation state is stable.

[0020]

As described above, according to the present invention, when a predetermined temperature atmosphere is obtained by cooling a gas and controlling the temperature of the cooled gas by a heater, a refrigeration circuit having an injection circuit used for cooling the gas is provided. So,
Compared to the case of using a conventional receiver, the amount of refrigerant can be greatly reduced, yet the condensed liquid refrigerant is easily and reliably supplied to the injection circuit to prevent abnormal temperature rise of the compressor and stabilize its operation state. Thus, it is possible to provide a refrigeration circuit including an injection circuit that can be operated.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of another embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of still another embodiment of the present invention.

FIG. 4 is a circuit configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 4 Expansion mechanism of this circuit 5 Evaporator 6 This circuit 7 Injection circuit 71 Injection expansion mechanism 8 Gas-liquid separator 81 Liquid refrigerant outlet of separator 8 82 Gas refrigerant outlet 91 of separator 8 92, 94 Gas-phase refrigerant return pipe 93 Expansion mechanism in gas-phase refrigerant return pipe 92 95 Expansion mechanism in gas-phase refrigerant return pipe 94

Claims (1)

(57) [Claims] 1. A refrigeration circuit provided with a injection circuit used for cooling of the gas in obtaining a predetermined temperature atmosphere by the temperature control of the heater and cooling the cooled gas in the gas, the refrigerant discharge port of the compressor Condenser, expander
The structure and the evaporator are sequentially connected by piping, and the refrigerant outlet of the evaporator
This circuit is connected to the refrigerant suction port of the compressor by piping.
Comprise and, a gas-liquid separator for gas-liquid separation part of the refrigerant discharged from the condenser branches connected to the the circuit in the condenser outlet side, the gas outlet of the gas-liquid separator A refrigeration circuit having an injection circuit, wherein the refrigeration circuit is connected back to the circuit and the liquid outlet of the gas-liquid separator is connected to an injection circuit including an expansion mechanism and connected to a compressor injection port.